This project is concerned with the development of statistical and mathematical methodology useful in the assessment of risks associated with exposures to potentially hazardous environmental and occupational agents. A major focal point is the generation of improved statistical techniques for estimating adverse human health effects from laboratory animal data, with particular emphasis being placed on dose-response modeling, low-dose extrapolation and extrapolation of toxicologic responses across species. Consideration is also given to the modeling of epidemiologic data in the risk assessment process. Current research efforts are concerned with the evaluation of a proposed procedure for estimating carcinogenic potency, with the investigation of factors that can affect the correlation of carcinogenic potency between mice and rats, with the assessment of the impact of litter effects on dose-response modeling in teratology, and with the extension of dose-response curves beyond the experimental dose range through the use of molecular dosimetry.